Substituted 5-amino-pyrazolo[4,3-e]-1,2,4-triazolo-[1,5-c]pyrimidine compounds disclosed in WO 01/92264 are useful as A2a receptor antagonists in the treatment of central nervous system diseases, in particular Parkinson's disease.
WO 01/92264 discloses processes for preparing 5-amino-2-substituted-pyrazolo[4,3-e]-1,2,4-triazolo-[1,5-c]pyrimidines comprising dehydrative rearrangement of hydrazines. Baraldi et al, J. Med. Chem., 41, (1998), p. 2126-2133 disclose formation of a 5-amino-pyrazolo[4,3-e]-1,2,4-triazolo-[1,5-c]pyrimidine having a phenylalkyl substituent at the 7-position, wherein the reaction comprises reacting a phenylalkyl-substituted hydrazide with (ethoxymethylene)malonitrile to form a substituted pyrazole. Baraldi et al, J. Med. Chem., 39, (1996), p. 1164-1171 disclose formation of a 7-substituted 5-amino-pyrazolo[4,3-e]-1,2,4-triazolo-[1,5-c]pyrimidine by reaction of an alkylated pyrazole with (ethoxymethylene)malonitrile. Both Baraldi et al process use NH2CN to accomplish the final ring closure.